Gas operation is a system of operation used to provide energy to operate autoloading firearms. In gas operation, a portion of high pressure gas from the cartridge being fired is used to power a mechanism to extract the spent case and chamber a new cartridge. Energy from the gas is harnessed through either a port in the barrel or a trap at the muzzle. This high-pressure gas impinges on a surface such as a piston head to provide motion for unlocking of the action, extraction of the spent case from the chamber, ejection of the spent case, cocking of the hammer or striker, chambering of a fresh cartridge, and locking of the action.
Most current gas systems employ some type of piston. The face of the piston is acted upon by gas from the combustion of the propellant from the barrel of the firearm. With a short-stroke or tappet system, the piston moves separately from the bolt group. It may operate through a connecting rod or assembly. The rod mechanically engages a bolt carrier impingement device, pushing the bolt carrier backward after the firing of the cartridge. The energy is imparted in a short, violent push, and the motion of the gas piston is then arrested by a return spring. This allows the bolt carrier assembly to continue through the operating cycle using kinetic energy.
While gas piston operating systems generally work well, the sharp impulse forces applied to the bolt carrier impingement device by the rod can be substantial. In fact, these forces can loosen the bolt carrier impingement device from the bolt carrier if the bolt carrier impingement device and bolt carrier are attached in a conventional manner.
An example of a firearm bolt carrier with mechanical/gas key that addresses this problem is found in U.S. Pat. No. 7,316,091 (Desomma). The Desomma patent discloses a bolt carrier that includes a buttress formed in a top surface. Although the Desomma patent provides improved strength of the junction between its key and bolt carrier, there are a number of potential disadvantages, at least for some applications. First, the bolt carrier must be modified to include a pocket cut in its top surface. Furthermore, the forward most portion of the key must be located rearward of the camming surface, which may require changes to the length of the connecting rod and/or other customization of the gas piston system.
It is therefore an object of this invention to provide a bolt carrier impingement device for a firearm that connects to a bolt carrier without requiring any fasteners to transfer forces from the bolt carrier impingement device to the bolt carrier.